The filter of the organic acids passive diffusion
sampler is impregnated in an alkali, which is dissolved in an aqueous solution after exposure and the extracted acetate and formate are determined by ion chromatography.
Reliability of nitrogen dioxide passive diffusion
tubes for ambient measurement: in situ properties of the triethanolamine absorbent, Journal of Environmental Monitoring 2: 307-312.
The ability of the placenta to deliver [O.sub.2] involves passive diffusion
and is determined partly by the physical dimensions (surface areas and effective diffusion distances) of the intervascular barrier and can be expressed as a total conductance (Mayhew et al., 1993; Ansari et al.
In view of the observed pH--solubility profile, for a 50% v/v propylene glycol:water vehicle, a pH between 4 and 5 was suggested by the authors to provide the most favourable environment for passive diffusion
since the concentration of unionised methotrexate would be optimal.
Here the effect of passive diffusion
was subtracted from the iontophoretic diffusion after calculating the passive diffusion
separately under identical conditions.
"Transdermal patches can have different designs but are meant to deliver drugs across the skin using passive diffusion
," said Bozena B.
Opiates, PCP, amphetamines, and cocaine enter oral fluid through passive diffusion
of the drug from the bloodstream into oral fluid.
We may only speculate that oral thyroxine is administered as sodium salt that is less lipophilic than the native hormone, which enters target cells both through passive diffusion
and in a carrier-mediated, inhibitable way.
Specifically, the objectives of this study were to evaluate: 1) the limiting nutrient of periphytic algae using a passive diffusion
periphytometer; 2) the content of easily exchangeable nutrients in sediments; and 3) sediment and water column dissolved P equilibrium in these streams.
Gas exchange is accomplished through the process of passive diffusion
of oxygen and carbon dioxide across the alveolar-capillary membrane.
The authors outline the mechanisms whereby secretion, active pumping, passive diffusion
or gradient diffusion at the cellular level cause nucleation on particulates, on cell surfaces, or genetically programmed precipitation in organic matrices either on or within cells.